The invention relates to ion detectors for mass spectrometry.
Historically, electron multiplier detectors, whether of the discrete or continuous dynode types, have been assembled in a ceramic and stainless steel housing by means of wires and mounting brackets. It has been generally believed that these materials are required in order to optimize performance in a vacuum environment (e.g., pumping speed, background noise level, etc.). These types of assemblies are typically highly labor intensive and also suffer from induced microphonics noise on the output signal. Microphonics results from vibration of the signal and power leads caused by the pumping system or other equipment. The mechanical vibration induces electrical noise pulses which are picked up on the signal lead and are subsequently amplified by the instrument electronics. This phenomenon results in an inherent limitation on the signal-to-noise performance of the instrument.
In some prior arrangements a vacuum compatible circuit board carrying discrete components has served as a support for a channel electron multiplier (CEM). Here the CEM is secured to the circuit board by straps that are epoxied to the board. External leads supply the CEM and circuit components, and the board is secured in placed by screws. This arrangement is also labor intensive because connections to other circuit components and the inputs and outputs and mounting of the circuit board on screw posts is done by hand.